[ARC5] ARC-2: IF Regeneration is a "No"

[Kenneth G. Gordon]

On 2 Apr 2014 at 8:19, Bruce Long wrote:

> Why does BW go up when the input and output caps are reduced in capacitance?
> 
> Decreasing the input and output DC blocking capacitors does - I think- increase
> the filter impedance but a higher filter impedance with the same value 5pF
> coupling capacitor means more coupling and larger bandwidth.

Yes. Of course! Good on ya, Bruce.

> Decreasing the coupling capacitance from 5 to 3pf is a quite significant change,
> ignoring strays, the 5-3 pf change is a 40% reduction in coupling

Ah HA! That makes absolute sense to me.

As I said, reduce the 5 pfd coupling cap.

BTW, Les sent me a couple of schematics of "top" vs "bottom" coupling 
which jogged my memory.

If you can reach the GROUND connections to the "bottoms" of the two coils 
in each IF can, you can lift that ground connection and insert a capacitor in 
series between that connection and ground. This results in "bottom" 
coupling. You may be able to do this completely externally to the IF cans.

You would then remove the 5pfd "top" coupling cap.

The bottom coupling cap would have to be around 1000 pfd to begin with, 
then adjust for max selectivity.

Ken W7EKB